The present invention relates to dynamoelectric machines in general and more particularly to improved end frame or end shield constructions.
One common form of dynamoelectric machine, such as small horsepower motors includes a stator housed in a shell and a rotor secured to a shaft, which is rotatably supported by one or more sleeve type bearings supported by end shield or end frame means that in turn are connected to and supported by the shell. Heretofore, known arrangements have included those where end shields or end frames abut against the shell at its ends, e.g., with a continuous or uninterrupted rabbet connection to complete the shell frame.
In practice, many end shields or end frames are formed of cast material or of relatively thick (e.g., 0.073 of an inch thick) stamped steel, but with rising material costs, it is desirable to make use of thinner steel (e.g., 0.056 of an inch, for purposes of comparison). However, end shields or end frames of existing designs and produced from thin steel would not be completely satisfactory because they would not be strong enough or rigid enough to provide a desired bearing mounting free from distortion caused by stresses transmitted from mounting bolt or through bolt locations to the bearing supporting region of the end frame. Accordingly, it would be desirable to provide a satisfactory end shield or end frame made of steel that is only one half to three-quarters as thick as has been used heretofore for a given motor frame size and which thus will offset rising material costs. Desirably, such improved end frame will also provide a close fitting rabbet that will not require machining, and will provide a structure of greater strength than a generally flat end shield (or frame) design of thicker material. Moreover, such end shield will desirably isolate possible distortion effects of clamp bolts from the bearing supporting portion of the end shield.